Ok this is really werid, I have a 1989 rx7 gtu. It drives great, but when I turn the headlights on it idles really low (it hasnt idled to the point where it dies), maybe around 100-300 rpms. But when i turn the lights off, it jumps back up to the 800-750 range.

Can anyone put any sense to this? I just got a 120,000 mile service and the mechanic said everything looks good.


thanks

 

you might need an alternater

 

Any load you put on the motor (either mechanically or electrically) will cause the idle to drop if your Bypass Air Conrtol Valve (BAC Valve) is either adjusted improperly or malfunctioning. Check the FSM found in the FAQ thread for ways of adjusting and checking this part.

There might be other problems with the car, but that is where I would start.

 

voltage?

 

could be due to poor grounds and/or BAC as rotary_rocket_87 said

 

BAC non-functional.

Tell you what. Idle the car til it's fully warmed up. At idle unplug the BAC's elect plug. I'll bet there is no change in your idle...............because the BAC isn't working.

That only applies if your present idle is 750 rpm or just below 750rpm.

 

sorry,but 100-300 rpm?i think the tach starts at 500.if it's above the first line (aside from 0) then that's either 500 or higher.